1. Field of the Invention
The present invention relates to an improved carabiner. More particularly, the present invention relates to a locking carabiner having a sleeve configured to reinforce and strengthen the carabiner.
2. State of the Art
Carabiners are used for various applications in many different activities. Carabiners are typically associated with outdoor recreational activities, such as rock climbing, mountaineering, mountain rescue work, and sailing. However, carabiners are also employed in applications such as rescue work in urban and industrial settings, safety restraints in urban and industrial settings, law enforcement work, and military applications among many other applications.
Generally, a carabiner has a ring, or C-shaped body, having a gate which may be opened to insert a rope, sling, or a belay/rappel device (e.g., a figure eight device or another belay/rappel device). The gate is shut, typically, by a spring which urges the gate closed. Often times, the gate may be further secured in a closed position by a locking mechanism known as a sleeve, which locks the gate to prevent opening thereof.
Typically, a carabiner having an elongated shape, such as an oval or a D-shape, exhibits load carrying capacities which differ significantly, depending on the direction of the applied load. FIG. 1A shows a carabiner 100 having a generally C-shaped body 102 and a gate 104 pivotally secured thereto at a rivet area 110 of the C-shaped body 102. The gate 104 may be pivoted to an open position as shown in FIG. 1A. The carabiner 100 is depicted having a sleeve 112 that may be employed to lock the gate 104 when it is closed. The gate 104 engages with a nose region 114 of the C-shaped body 102 when in a closed position, shown in FIG. 1B and in cross-section in FIG. 2. The gate 104 includes a receptacle 116 for receiving the nose region 114, which may flare outward at the proximal end 120, to abut the gate 104 during loading of the carabiner 100. A carabiner having such a gate/nose interface may be referred to as a keylock carabiner. The load carrying capacity of the carabiner 100 is greatest along its major axis 106 and it exhibits a significantly reduced carrying capacity along its minor axis 108 (i.e., when cross-loaded).
Testing conducted on conventional carabiners has shown the point of failure during tensile loading along the major axis 106 to be located at the pivoting rivet area 110, the gate 104, or the nose region 114. FIG. 3 shows a conventional keylock carabiner 101 exhibiting failure at the nose region 114. The failure point is the narrowest portion 118 of the nose region 114, between the carabiner body 102 and the outward flaring proximal end 120 of the nose region 114. FIG. 4 depicts a conventional keylock carabiner 103 exhibiting another mode of failure. Flanges 122 on either side of the receptacle 116 of the gate 104 have been forced apart by the outward flaring proximal end 120 of the nose region 114 during tensile loading of the carabiner. Arrows on FIG. 4 depict the direction of deformity of the flanges 122. FIG. 5 depicts another view of the failed gate 104, with a longitudinal crack 124 through the gate 104, in the region behind the receptacle 116.
The thickness of the nose region 114 of the carabiner 100 may be increased, increasing the strength of the nose region 114, to avoid the mode of failure shown in FIG. 3. However, the receptacle 116 is a female recipient, sized and configured to mate with and engage the male nose region 114, and must likewise be increased in size. Increasing the size of the receptacle 116 requires the width of the flanges 122 to be decreased, or the overall diameter of the gate 104 must be increased. Decreasing the width of flanges 122 will cause a carabiner to be further susceptible to the mode of failure shown in FIGS. 4 and 5. Increasing the overall diameter of the gate 104 is undesirable because the size of the gate opening will be decreased. The thicker nose region or the increased gate diameter may prevent the carabiner from threading through an aperture of an external object, if the nose region or gate has a diameter larger than that of the aperture. This may be a disadvantage, preventing a user from attaching the carabiner to the external object, or prevent the carabiner from rotating to a desired position with respect to the external object. Another disadvantage of increasing the overall diameter of the gate is the additional material required, increasing the cost and the weight of the carabiner.
Accordingly, there is a need for a carabiner having increased strength during tensile loading.